Study of the spectrophotometric measurement of lithium using TMC-crown formazane

Lower Rim Substituted tert‐Butyl Calix[4]Arenes (Part IV). Calix[4]Arene‐Crown Ethers as Ionophores in Plasticized PVC‐Membrane Electrodes

“…The first calix-crown compound: p-tert-butylcalix [4]arene-crown-6, with polyethylenoxy bridge between the distal [1,3] phenolic OH groups was synthesized by Alfieri et al in the reaction of pentaethylenoxyglycol ditosylate and p-tert-butylcalix [4]arene under basic conditions [1]. Calix-crown compounds are of interest to us as ion-sensing compounds [2,3].…”

“…Calix-crown compounds are of interest to us as ion-sensing compounds [2,3]. There are not many cesium ionophores reported in literature [4,5]. The compounds which have high Cs /Na selectivity are of special need for sensing Cs cations in radioactive wastes.…”

“…The selectivity of complexation depends on the length of the polyether chain and it shows a complementarity effect between the size of the cavity and the cation size [7 ± 9]. Yamamoto et al have reported that the corresponding p-tert-butylcalix [4]arene with shorter polyethylenoxy bridge, the tert-butyl-25,27-diethoxy-calix [4]crown-4 shows a very high Na /K selectivity in ion-selective electrodes (log K pot Na/K À 5.0) [10,11]. The ionophoric properties of p-tert-butyl-25,27-bisethoxy-calix [4]arene-crown-5 [12] and the selectivities for alkali metal ions were studied in ISFETs (ion-selective field effect transistors) [13] and they strongly depend on the stereochemistry around the bridging region.…”

“…Calix [4]arene-crown ether derivatives are compounds which combine the lipophilic tert-butylcalix [4]arene and electrondonoring polyethylenoxy macroring in one structure. The first calix-crown compound: p-tert-butylcalix [4]arene-crown-6, with polyethylenoxy bridge between the distal [1,3] phenolic OH groups was synthesized by Alfieri et al in the reaction of pentaethylenoxyglycol ditosylate and p-tert-butylcalix [4]arene under basic conditions [1].…”

“…The ionophoric properties of p-tert-butyl-25,27-bisethoxy-calix [4]arene-crown-5 [12] and the selectivities for alkali metal ions were studied in ISFETs (ion-selective field effect transistors) [13] and they strongly depend on the stereochemistry around the bridging region. Distally substituted calix [4]-crowns can exist in three different conformations: cone, partial cone and 1,3-alternate. Changes in molecule conformation cause the changes in the effective size of the polyethylene ether loop.…”